// Copyright 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_
#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_

#include "base/base_export.h"
#include "base/mac/scoped_cffiledescriptorref.h"
#include "base/mac/scoped_cftyperef.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "base/message_loop/message_pump_mac.h"
#include "base/threading/thread_checker.h"

namespace base {

// This file introduces a class to monitor sockets and issue callbacks when
// sockets are ready for I/O on iOS.
class BASE_EXPORT MessagePumpIOSForIO : public MessagePumpNSRunLoop {
public:
    // Used with WatchFileDescriptor to asynchronously monitor the I/O readiness
    // of a file descriptor.
    class Watcher {
    public:
        // Called from MessageLoop::Run when an FD can be read from/written to
        // without blocking
        virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
        virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;

    protected:
        virtual ~Watcher() { }
    };

    // Object returned by WatchFileDescriptor to manage further watching.
    class FileDescriptorWatcher {
    public:
        FileDescriptorWatcher();
        ~FileDescriptorWatcher(); // Implicitly calls StopWatchingFileDescriptor.

        // NOTE: These methods aren't called StartWatching()/StopWatching() to
        // avoid confusion with the win32 ObjectWatcher class.

        // Stop watching the FD, always safe to call.  No-op if there's nothing
        // to do.
        bool StopWatchingFileDescriptor();

    private:
        friend class MessagePumpIOSForIO;
        friend class MessagePumpIOSForIOTest;

        // Called by MessagePumpIOSForIO, ownership of |fdref| and |fd_source|
        // is transferred to this object.
        void Init(CFFileDescriptorRef fdref,
            CFOptionFlags callback_types,
            CFRunLoopSourceRef fd_source,
            bool is_persistent);

        void set_pump(base::WeakPtr<MessagePumpIOSForIO> pump) { pump_ = pump; }
        const base::WeakPtr<MessagePumpIOSForIO>& pump() const { return pump_; }

        void set_watcher(Watcher* watcher) { watcher_ = watcher; }

        void OnFileCanReadWithoutBlocking(int fd, MessagePumpIOSForIO* pump);
        void OnFileCanWriteWithoutBlocking(int fd, MessagePumpIOSForIO* pump);

        bool is_persistent_; // false if this event is one-shot.
        base::mac::ScopedCFFileDescriptorRef fdref_;
        CFOptionFlags callback_types_;
        base::ScopedCFTypeRef<CFRunLoopSourceRef> fd_source_;
        base::WeakPtr<MessagePumpIOSForIO> pump_;
        Watcher* watcher_;

        DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
    };

    enum Mode {
        WATCH_READ = 1 << 0,
        WATCH_WRITE = 1 << 1,
        WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
    };

    MessagePumpIOSForIO();
    ~MessagePumpIOSForIO() override;

    // Have the current thread's message loop watch for a a situation in which
    // reading/writing to the FD can be performed without blocking.
    // Callers must provide a preallocated FileDescriptorWatcher object which
    // can later be used to manage the lifetime of this event.
    // If a FileDescriptorWatcher is passed in which is already attached to
    // an event, then the effect is cumulative i.e. after the call |controller|
    // will watch both the previous event and the new one.
    // If an error occurs while calling this method in a cumulative fashion, the
    // event previously attached to |controller| is aborted.
    // Returns true on success.
    // Must be called on the same thread the message_pump is running on.
    bool WatchFileDescriptor(int fd,
        bool persistent,
        int mode,
        FileDescriptorWatcher* controller,
        Watcher* delegate);

    void RemoveRunLoopSource(CFRunLoopSourceRef source);

private:
    friend class MessagePumpIOSForIOTest;

    void WillProcessIOEvent();
    void DidProcessIOEvent();

    static void HandleFdIOEvent(CFFileDescriptorRef fdref,
        CFOptionFlags callback_types,
        void* context);

    ThreadChecker watch_file_descriptor_caller_checker_;

    base::WeakPtrFactory<MessagePumpIOSForIO> weak_factory_;

    DISALLOW_COPY_AND_ASSIGN(MessagePumpIOSForIO);
};

} // namespace base

#endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_
